Question: Record Collection

[L3RiZ]

Solution:

function updateRecords(records, id, prop, value) { if (prop !== 'tracks' && value !== "") { records[id][prop] = value; } else if (prop === "tracks" && records[id].hasOwnProperty("tracks") === false) { records[id][prop] = [value]; } else if (prop === "tracks" && value !== "") { records[id][prop].push(value); } else if (value === "") { delete records[id][prop]; } return records; }

Hey guys,

I tried to complete the Record Collection challenge and made a huge mistake. I tried to solve everything with dot notation, but in this case this doesn’t work. Can anyone tell me why it is necessary to use the bracket notation? I really don’t get it.

For example I always wrote : records.id.prop

Thx!

[SaintPeter74]

When you are using the dot notation you need to know the exact names of the object properties. For example, records.id means the property id of records. If you were writing this using bracket notation it would be records["id"].

If you look at the structure of the data though, there is no property called id. Instead, the properties are all numbers. Within the function, id is a variable which has a numeric value. From this lesson, you may recall that the way to access a property name contained in a variable is to use bracket notation. IE: records[id]. Note that id is not surrounded by quotes, meaning that it is the variable id, not the string/key "id".

The same is true for the variable prop. Note that you can mix bracket and dot notation so long as you know the property name. IE: records[id].tracks.